I'm interested to see what you did to mount the piston for the bed to get it to work. I've been toying with the idea of installing one on my utility trailer for it's tilt bed so that the tilt can be controlled instead of being at the mercy of gravity and where the weight on the bed is at the time. I want to make it a manual pump system instead of a powered system though. So, I'm more interested in the piston setup than the pump and tank.
Some hydraulics 101:
Liquids, i.e. water, hydraulic fluid, are incompressible, but they will turn into gas which will both expand and compress. So, if you don't want a hydraulic cylinder to be able to expand uncontrolled, you need to have a dual acting one - i.e. one with both input and exhaust ports. Then, of course, you need input and output hoses, and a double acting control valve. In most cases, i.e. assuming proper design, the risk of uncontrolled lift is minimal, so single acting is used, which it appears to be case for
@Aeroflex truck - only one line to cylinder.
In a trailer or dump truck, where >60% of the weight is ahead of the axle, and pivot point is very close to the rear of the box, you usually don't have an issue.
But I have seen a couple spectacular failures, where the box was mounted 50/50 and pivot point was moved forward a few feet. (4 ton truck being stuck in grain elevator, with front wheels >6' in air and box wedged in rafters, being the most vivid)*.
Note: a pickup box is mounted ~50/50 and if loaded with heavy material e.g. sticky, wet clay, you can get into similar situation.
The portion of
@Aeroflex solution I am most interested in, is the reinforcement of both the pickup bed and the rear frame. A pickup frame being designed to collapse in event of accident has been known to do so when overloaded by dump box/the pickup box counts on the truck frame for much of its strength.
*Thereafter the individual used jack stands a rear end of frame to prevent a reoccurrence & unloaded slower. That was less expense than the extra cost of all the extra components for a double acting solution.
p.s. On farm, our solution to the air compressor not being able to keep up with paint sprayer, was a couple expired 100lb propane cylinders. While they might not have been legal for holding propane anymore, they held enough compressed air for what we needed and cost was right. Something similar with handful of 20lb ex-barbeque tanks is probably easier for most people. Compressor would run for quite a while while we got ready. And you knew when it cut back in, it was time to stop.
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